Aspects of the disclosure provide an amplifier system and a method for dynamically cancelling an offset voltage. The amplifier system includes a chopper amplifier system that includes a differential amplifier with an offset calibration circuit. The chopper amplifier system is configured to generate an output signal including voltage variations indicating an offset voltage of the differential amplifier. The amplifier system also includes a feedback circuit configured to determine a polarity of the offset voltage of the differential amplifier based on the output signal, and to transmit a control signal to the offset calibration circuit to reduce the offset voltage of the differential amplifier.

A voltage-current converter includes a first input stage and a second input stage with a first transistor and a second transistor driven by the first input stage and by the second input stage, respectively. First and second current generators are coupled to current lines of the first transistor and of the second transistor. At least one resistor couples the current lines of the first transistor and of the second transistor, where the ends of the aforesaid resistor are coupled to feedback terminals of the input stages so that an input voltage applied between voltage input terminals of the input stages is converted into a current on respective current output terminals of the converter. The converter includes switching circuits for coupling the first and second current generators alternately to the current line of the first transistor and to the current line of the second transistor.

When the offsets of the first and second differential units have polarities different from each other, the first and second differential units are both set to a normal connection state, i.e., a state in which the input voltage is supplied to the first input terminal of each of the first and second differential units and the output voltage is supplied to the second input terminal of each of the first and second differential units. When the offsets of the first and second differential units have the same polarity, on the other hand, the first differential unit is set to the above normal connection state and the second differential unit is set to a chopping connection state in which the output voltage is supplied to the first input terminal and the input voltage is supplied to the second input terminal.

A voltage-current converter includes a first input stage and a second input stage with a first transistor and a second transistor driven by the first input stage and by the second input stage, respectively. First and second current generators are coupled to current lines of the first transistor and of the second transistor. At least one resistor couples the current lines of the first transistor and of the second transistor, where the ends of the aforesaid resistor are coupled to feedback terminals of the input stages so that an input voltage applied between voltage input terminals of the input stages is converted into a current on respective current output terminals of the converter. The converter includes switching circuits for coupling the first and second current generators alternately to the current line of the first transistor and to the current line of the second transistor.

An output stage of a buffer or an amplifier connected to a switched capacitive load can operate in two phases to perform precharging and fine settling. The precharging and fine settling phases can be synchronized to the switching phases of the switched capacitive load connected to the amplifier. During the precharging phase, the output stage can be disconnected from the prior stages of the amplifier, and the output node of the amplifier can be connected to the switched capacitive load to precharge the capacitive load with the voltage already stored in the output stage. During the fine settling phase, the output stage can be reconnected to the prior stages of the amplifier, and the amplifier nodes can settle and get ready for sampling, which can occur at the end of the fine settling phase.

An output stage of a buffer or an amplifier connected to a switched capacitive load can operate in two phases to perform precharging and fine settling. The precharging and fine settling phases can be synchronized to the switching phases of the switched capacitive load connected to the amplifier. During the precharging phase, the output stage can be disconnected from the prior stages of the amplifier, and the output node of the amplifier can be connected to the switched capacitive load to precharge the capacitive load with the voltage already stored in the output stage. During the fine settling phase, the output stage can be reconnected to the prior stages of the amplifier, and the amplifier nodes can settle and get ready for sampling, which can occur at the end of the fine settling phase.

Adaptive biasing circuits for input differential pairs of a buffer or an amplifier adapt to autozero currents for discrete pair selection or continuous pair selection. The adaptive biasing circuits include a multistage device including current source and follower devices with a plurality of switches for a two-phase operation: autozero and amplifying phases. During an autozero phase, input differential pairs are isolated from subsequent stages and biasing currents are determined for autozeroing of input offset voltages. During an amplifying phase, both input differential pairs can be coupled to subsequent stages for continuous selection or a selected input differential pair can be coupled to subsequent stages for discrete selection.

An input stage for a signal processing circuit, the input comprising: a first differential pair; and a second differential pair; wherein the first differential pair and the second differential pairs have opposing skews which controls a voltage offset of the input stage.

An example device includes: switch circuitry configured to: connect, in a first state based on a control signal, a first switch input to a first switch output and a second switch input to a second switch output; and connect, in a second state based on the control signal, the first switch input to the second switch output and the second switch input to the first switch output; an operational amplifier configured to: generate, in response to the control signal, a first voltage based on a gain and the connections in the first state; and generate, in response to the control signal, a second voltage based on the gain and the connections in the second state; and an Analog to Digital Converter (ADC) configured to convert the first voltage and the second voltage into a digital value based on a multiplication of the input voltage and the gain.